FIA Releases Gaseous Systems Guides
The first, single-sheet document, FIA Fact File 0041, details information about likely changes in the need for annual checking of pressure gauge calibration for inert gas containers. Previously, wherever pressure gauges or weighing devices are used to monitor the contents of inert gas cylinders, the requirements of BS EN 15004 stipulate that these devices should be compared to a separate calibrated device at least annually. But for practical reasons, the UK delegation has made representations to the ISO technical committee to remove this requirement of annual comparison (by deleting the last sentence of clause 9.2.1.3.b). It is reliably anticipated that this change will be implemented within ISO 14520, which, in turn, will subsequently be reflected by changes to the European standard BS EN 15004.
The second Fact File, number 0042, imparts information about the decision taken at ISO TC 21 SC8 meetings, where it was agreed that in the next revision of ISO 14520, the wording relating to hold time heights in protected enclosures would be: “At the end of the hold time, the extinguishant concentration at the height of the highest hazard shall not be less than 85% of the design concentration”. This change is also expected to be appear in subsequent amendments to the EN standard, 15004.
The three-page guidance document on "The Use of High and Regular Hazard Concentrations for Enclosures Protected by Gaseous Fire Extinguishing Systems, provides the clarification that some people believe is needed in differentiating between ‘regular’ and ‘high’ hazards contained in Clause 7.5.1.3 of BS EN 15004. Regular and high hazard necessitate different agent concentrations. So, the correct interpretation is vital in ensuring that the end-user is supplied with a system delivering the appropriate concentration. In the guidance document, a number of different scenarios is discussed and guidance based on those scenarios.
The effectiveness of a ‘total-flooding’, fire fighting system depends on retention of the air-extinguishant mixture for the appropriate, designated amount of time. In the twenty six-page “Guidance on the Pressure Relief and Post-discharge Venting of Enclosures Protected by Gaseous Fire Fighting Systems”, the management of pressure during discharge and the retention of the extinguishant mixture within the protected area for that specified period, are both discussed. The document provides guidance on fulfilling the requirements of BS EN 15004-1 and BS 5306-4, in respect of over-pressure and under-pressure venting, as well as post-discharge extraction. It considers the design, selection and installation of vents to safeguard the structural integrity of enclosures protected by such systems.
Aiming to keep its members and the general market informed on developments in UK legislation, the FIA passes on technical knowledge and fire safety advice as well as providing training. All of the FIA guides are intended to provide general guidance and are not intended to be a substitute for detailed advice in specific circumstances.
Further Details: Becky Reid, FIA, Tudor House, Kingsway Business Park,
Oldfield Rd, Hampton, Middlesex, TW12 2HD
Tel: 020 3166 5002 Fax: 020 8941 0972
E-mail: info@fia.uk.com
Website: www.fia.uk.com
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